Light Guide Structure with Multiple Entrances

ABSTRACT

The light communication solution presented herein uses waveguides with multiple entrances to efficiently collect light used for light communications and propagate that collected light to a sensor. To that end each waveguide entrance, or at least all but the initial waveguide entrance, is configured to not only collect and input the light into the TIR waveguide, but also to maintain TIR of light already propagating within the TIR waveguide. In so doing, the solution presented herein increases the amount of light available for light communications. Further, because each waveguide may channel light from multiple collection points to a single sensor, the solution presented herein reduces the number of sensors needed for the light communications. The solution presented herein facilitates the implementation of light communications for a wide variety of devices (e.g., cellular telephones, tablets, smartphones, smart watches, smart glasses, etc.) and/or in a wide variety of scenarios.

BACKGROUND

WiFi is a wireless technology that uses electromagnetic waves towirelessly connect multiple devices within a particular area to eachother and/or to connect one or more wireless devices within a particulararea to the internet. While WiFi has been incredibly useful and popularin recent years, it is expected that the need for more bandwidth willsoon lead to replacing WiFi or complementing WiFi with alternativewireless technologies.

Light Fidelity (LiFi), which uses light within certain wavelength rangesfor local area wireless communications, represents one alternativewireless technology that may replace or complement WiFi. LiFi systemsrely on visible, infrared, and/or near ultraviolet spectrum waves. Bymodulating a light source, e.g., a light emitting diode, a LiFitransmitter transmits high speed signals detectable by a photodetector.The photodetector converts the detected light to electrical current,which is further processed by the receiver to interpret the detectedlight.

The visible light spectrum is ˜10,000 times larger than the radiofrequency spectrum. LiFi is therefore expected to increase the bandwidthachievable by WiFi alone by a factor of 100. Further, LiFi tends to bemore suitable in high density and/or high interference environments,e.g., airplanes, office buildings, hospitals, power plants, etc. Thus,considerable focus has recently been given to improving LiFi technologyand/or adapting LiFi technology for specific applications and/ordevices.

SUMMARY

The solution presented herein uses waveguides with multiple entrances toefficiently collect light used for light communications and propagatethat collected light to a sensor. In so doing, the solution presentedherein increases the amount of light available for light communications.Further, because each waveguide may channel light from multiplecollection points to a single sensor, the solution presented hereinreduces the number of sensors needed for the light communications. Thewaveguide solution presented herein may be implemented inside a deviceand/or along an exterior surface, e.g., housing or casing, of a device.As such, the solution presented herein also enables the implementationof light communications for a wide variety of devices (e.g., cellulartelephones, tablets, smartphones, smart watches, smart glasses, etc.)and/or in a wide variety of scenarios.

One exemplary embodiment comprises a detection system for lightcommunications. The detection system comprises a total internalreflection (TIR) waveguide and a light sensor. The TIR waveguidecomprise a first structure, a diffusive element, and two or morewaveguide entrances. The first structure has a first index ofrefraction, where a second index of refraction abutting the firststructure is less than the first index of refraction such that lightinput to the TIR waveguide propagates along the TIR waveguide within thefirst structure. The diffusive element is disposed along an internaledge of the first structure at a first location of the TIR waveguide,and is configured to disrupt the propagation of the light along the TIRwaveguide. The two or more waveguide entrances are each at acorresponding location offset in a first direction along the TIRwaveguide from the first location. Each of the two or more waveguideentrances is configured to collect light associated with the lightcommunications and input the collected light to the first structure atthe corresponding second location to propagate the collected light tothe first location. At least one of the two or more waveguide entrancesis further configured to maintain TIR of the light already propagatingalong the TIR waveguide within the first structure. The light sensor isdisposed adjacent an edge of the first structure opposite the firstlocation and spaced from the diffusive element by a thickness of thefirst structure. The light sensor is configured to detect the disruptedlight.

One exemplary embodiment comprises a method of detecting lightassociated with light communications. The method comprises collectinglight configured for the light communications via two or more waveguideentrances disposed at different locations along a total internalreflection (TIR) waveguide. The TIR waveguide comprises a firststructure having a first index of refraction, where a second index ofrefraction abutting the first structure is less than the first index ofrefraction such that light entering the TIR waveguide propagates alongthe TIR waveguide within the first structure. The method furthercomprises maintaining, at each of at least one of the two or morewaveguide entrances, TIR of light already propagating along the TIRwaveguide within the first structure. The method further comprisesdisrupting the propagation of the light along the TIR waveguide using adiffusive element disposed along an internal edge of the first structureat a first location of the TIR waveguide, said first location offsetalong the TIR waveguide from each of the locations of the two or morewaveguide entrances. The method further comprises detecting thedisrupted light using a light sensor disposed adjacent an edge of thefirst structure opposite the first location and spaced from thediffusive element by a thickness of the first structure.

One exemplary embodiment comprises a portable device configured to beworn and/or carried by a user. The portable device comprises a detectionsystem for light communications, which comprises a total internalreflection (TIR) waveguide and a light sensor. The TIR waveguidecomprise a first structure, a diffusive element, and two or morewaveguide entrances. The first structure has a first index ofrefraction, where a second index of refraction abutting the firststructure is less than the first index of refraction such that lightinput to the TIR waveguide propagates along the TIR waveguide within thefirst structure. The diffusive element is disposed along an internaledge of the first structure at a first location of the TIR waveguide,and is configured to disrupt the propagation of the light along the TIRwaveguide. The two or more waveguide entrances are each at acorresponding location offset in a first direction along the TIRwaveguide from the first location. Each of the two or more waveguideentrances is configured to collect light associated with the lightcommunications and input the collected light to the first structure atthe corresponding second location to propagate the collected light tothe first location. At least one of the two or more waveguide entrancesis further configured to maintain TIR of the light already propagatingalong the TIR waveguide within the first structure. The light sensor isdisposed adjacent an edge of the first structure opposite the firstlocation and spaced from the diffusive element by a thickness of thefirst structure. The light sensor is configured to detect the disruptedlight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary waveguide-based light detection systemaccording to exemplary embodiments of the solution presented herein.

FIG. 2 shows an exemplary waveguide entrance according to exemplaryembodiments of the solution presented herein.

FIG. 3 shows an exemplary waveguide-based light detection systemaccording to further exemplary embodiments of the solution presentedherein.

FIG. 4 shows an exemplary waveguide-based light detection systemaccording to further exemplary embodiments of the solution presentedherein.

FIG. 5 shows an exemplary waveguide-based light detection systemaccording to further exemplary embodiments of the solution presentedherein.

FIG. 6 shows an exemplary method for detecting light for lightcommunications according to exemplary embodiments of the solutionpresented herein.

FIGS. 7A-7C show an exemplary device comprising the light detectionsystem according to exemplary embodiments of the solution presentedherein.

FIG. 8 shows an exemplary device comprising the light detection systemaccording to further exemplary embodiments of the solution presentedherein.

FIG. 9 shows an exemplary device comprising the light detection systemaccording to further exemplary embodiments of the solution presentedherein.

DETAILED DESCRIPTION

The use of light communications, e.g., LiFi, with WiFi or as areplacement for WiFi, has expanded the capabilities of local areawireless communications. However, the devices typically preferable forsuch communications are small, and have limited space available for thedetectors/receivers used for such communications. Further, the spaceavailable in these devices continues to decrease due to the continualreduction in size of these devices and/or the continual addition of newfeatures and/or hardware into these devices. For example, wearabledevices (e.g., glasses, watches, etc.) are designed to have a minimalsize to improve their wearability (e.g., make them lighter, morecomfortable, etc.). The limited physical size of many devices,especially when combined with all the functionality intended to beincluded in such devices, places limitations on the location and/or sizeand/or number of light sensors that may be included in a lightcommunication device.

Conventional light communication solutions require a sensor for everylight capturing/entrance location of a device. For example, a devicethat implements light communications may include three openings in ahousing of the device, where such openings are intended to, or could beused to, receive external light associated with light communications. Ina conventional solution, such a device necessarily includes threesensors, one sensor disposed beneath each of the three openings, tocapture the light entering each opening. Because many devices havelimited space available for such sensors, such conventional solutionsseverely limit the number of sensors available for light communications,and thus limit the amount of light that can be collected for lightcommunications and/or the effectiveness of light communications.Further, conventional solutions generally have challenging mechanicalrequirements regarding the location of the sensor and/or alignment of asensor with the corresponding opening in order to enable the sensor tocapture as much of the light entering the opening as possible. Thesemechanical limitations may severely limit the location options for theopenings.

The solution presented herein solves many problems associated withconventional solutions by using waveguides to channel light from two ormore openings to a sensor. In so doing, the solution presented hereinreduces the number of sensors used for light communications, enableseach sensor to capture more light associated with the lightcommunications, and/or enables flexibility regarding the sensor size,the sensor location in the device, and/or the alignment of the sensorwith any particular opening. In particular, the solution presentedherein enables any number of openings to be placed anywhere on thedevice, while also enabling one or more sensors to be placed at anysuitable location within the device, which improves the signal qualityand reduces the mechanical constraints associated with LiFi.

FIG. 1 shows one exemplary light detection system 100 for lightcommunications according to embodiments of the solution presentedherein. The light detection system 100 comprises a waveguide 110 and alight sensor 130. The waveguide 110 comprises a Total InternalReflection (TIR) structure 112 through which light propagates, adiffusive element 114, and two waveguide entrances 120. Light capturedat each waveguide entrance 120 propagates through the waveguide 110within the TIR structure 112, including when it encounters anotherwaveguide entrance 120, until it encounters the diffusive element 114.The diffusive element 114 disrupts the propagation of the light toenable detection of the light by sensor 130. The following uses genericreference numbers to generally refer to different elements, and adds aletter designation to refer to a specific one of multiple ones of thesame elements. It will be appreciated that FIG. 1 only shows twowaveguide entrances 120 for illustrative purposes; additional waveguideentrances 120 may be included, as discussed further below.

The propagation of the light through the TIR structure 112 is at leastpartially controlled by the index of refraction n₁ of the TIR structure112 relative to the surrounding index/indices of refraction. Whenmaterial(s) surrounding the TIR structure 112 has/have a lowerrefractive index than the TIR structure 112, the TIR structure 112functions as a TIR layer, which enables the light entering the TIRstructure 112 at a TIR angle to propagate along the TIR structure 112with total internal reflection, and thus with minimal-to-no loss. Thus,the TIR structure 112 has a first index of refraction n₁, where indicesof refraction, e.g., n₂ and/or n₃, surrounding/adjacent to the TIRstructure 112 is/are less than the first index of refraction n₁ suchthat light input to the waveguide 110 propagates along the waveguide 110within the TIR structure 112. While in some embodiments the indices ofrefraction surrounding the TIR structure 112 are all the same, thesolution presented herein does not require the index/indices ofrefraction surrounding the TIR structure 112 to be equal. Instead thesolution presented herein only requires that the index of refraction n₁of the TIR structure 112 be greater than each index of refraction of thesurrounding material so that light input into the TIR structure 112propagates along the TIR structure 112 with total internal reflection.

The desired index of refraction relationship between the TIR structure112 and the surrounding structure(s)/material(s) may be achieved in anynumber of ways. For example, when the TIR structure 112 is a cylindricaltube having a first index of refraction n₁, having a second index ofrefraction n₂ surrounding the tube less than the first index ofrefraction (n₂<n₁) causes the desired total internal reflection in theTIR structure 112. In another example, when the TIR structure 112 is aright rectangular prism having the first index of refraction n₁, havinga second index of refraction n₂ on one side of the TIR structure 112that is less than the first index of refraction (n₂<n₁), and a thirdindex of refraction n₃ on an opposing side of the TIR structure 112 thatis also less than the first index of refraction (n₃<n₁), as shown inFIG. 1 , causes total internal reflection in the TIR structure 112. Inanother example, waveguide 110 may be realized using a set of coatingsor layers, where each layer/coating represents a different part of thewaveguide 110. In this example, one layer may represent a TIR layer(i.e., the TIR structure 112), while one or more layers surrounding theTIR layer has a lower index of refraction than that of the TIR layer,and thus represents a “reflective” layer. Such a reflective layer mayalso serve as a protective layer that protects the TIR structure 112,e.g., from scratches, debris, and/or other foreign objects.Alternatively, a protective layer separate from the reflective layer maybe applied between the TIR structure 112 and the reflective layer, wherethe protective layer has the same or lower index of refraction as thereflective layer. The protective layer may also be used to add print(e.g., text, images, etc.) that when visible to a user of the device 200identify any desired information related to or about the device 200,e.g., brand name, model name/number, team affiliations, schoolaffiliations, etc.

Diffusive element 114 is disposed along an internal edge of the TIRstructure 112 at a predetermined location of the waveguide 110 todisrupt the propagation of the light along the TIR structure 112 fordetection by the light sensor 130. The diffusive element 114 comprisesany material or structure that disrupts the propagation of the lightwithin the TIR structure 112. In some embodiments, the diffusive element114 may direct the disrupted light to the sensor 130. In otherembodiments, the diffusive element 114 may scatter the light such thatat least some of the originally propagating light is captured by thesensor 130. In one exemplary embodiment, the diffusive element 114comprises white or colored paint applied to the inner edge of the TIRstructure 112 above the sensor 130. In another exemplary embodiment, thediffusive element 114 is constructed by altering the material at thelocation of diffusive element 114 so that this location of the TIRstructure 112 is no longer flat and/or smooth. For example, machineddots may be placed at the location of the diffusive area 114 or thelocation of the diffusive area 114 may be etched or roughened.

The light sensor 130 is disposed adjacent to an internal edge of the TIRstructure 112 opposite the location of the diffusive element 114 andgenerally spaced from the diffusive element by a thickness t of the TIRstructure 112 so that the light sensor 130 detects the disrupted light.Light sensor 130 comprises any light sensor configured to detect thelight disrupted by the diffusive element, e.g., a Photo SensitiveReceptor (PSR).

Each waveguide entrance 120 comprises an opening in the housing of adevice 200 so as to collect light 140, e.g., associated with lightcommunications, and input the collected light to the TIR structure 112of the waveguide 110. Further, each waveguide entrance 120 is laterallyoffset from the location of the diffusive element 114/sensor 130, wherelight 140 collected at one entrance propagates along the waveguide 110to the sensor 130. For example, waveguide entrance 120 a, which islaterally offset along the waveguide 110 from the location of thediffusive element 114, collects the proximate light 140 a, whilewaveguide entrance 120 b, which is laterally offset along the waveguide110 between waveguide entrance 120 a and the diffusive element 114, asshown in FIG. 1 , collects and inputs the proximate light 140 b. Thelight 140 a collected at waveguide entrance 120 a propagates as light116 a within the TIR structure 112, while the light 140 b collected atwaveguide entrance 120 b propagates as light 116 b within the TIRstructure 112.

According to the solution presented herein, each waveguide entrance 120in one exemplary embodiment, or at least all but the waveguide entrancefarthest from the diffusive element 114 along the TIR waveguide 110(e.g., an initial waveguide entrance 120 a at one end of the TIRwaveguide 110), is configured to maintain the TIR of light alreadypropagating within the TIR structure 112, in addition to collecting anddirecting external light 140 into the TIR structure 112. To that end,each waveguide entrance 120, or at least all but the initial waveguideentrance 120 a, comprises a light guide structure 122.

FIG. 2 shows an exemplary waveguide entrance 120 that includes a lightguide structure 122. As shown in FIG. 2 , the light guide structure 122redirects the light collected by the waveguide entrance 120 such thatthe collected light 140 enters the TIR structure 112 at a total internalreflection angle to facilitate propagation of the collected light withinthe TIR structure, e.g., along path 116 b. To continue the propagationof the light already within the TIR structure 112, e.g., along path 116a, the surface of the light guide structure 122 abutting the TIRstructure 112 is configured to maintain the total internal reflection ofthe light already propagating within the TIR structure 112. In so doing,the solution presented herein enables the sensor 130 to detect lightfrom multiple paths of light 116 a, 116 b collected at multiplewaveguide entrances 120 a, 120 b.

Various techniques may be used to configure the light guide structure122 to collect and input the light 140 into the TIR structure 112, whilealso maintaining the propagation of light already in the TIR waveguide110 within the TIR structure 112. For example, the surface of the lightguide structure 122 abutting the TIR structure 112 may be polished toalign with the TIR structure 112 to prevent the already propagatinglight from experiencing any irregular reflections, where an index ofrefraction of this surface, i.e., the side of the light guide structure122 abutting the TIR structure 112, is less than the index of refractionof the TIR structure 112. In other exemplary embodiments, the surface ofthe light guide structure 122 abuts the TIR structure 112 via a coatinghaving an index of refraction less than that of the TIR structure 112.In either case, this may mean the index of refraction of the surface ofthe light guide structure 122 abutting the TIR structure 112 is equal tothe index of refraction of the surrounding TIR waveguide, e.g., equal ton₂ or equal to n₃. According to one exemplary embodiment, light guidestructure 122 comprises a dual index element, where the light enteringthe light guide structure 122 passes through a material 122 ₁ having afirst light guide index n_(G1) to a material 122 ₂ having a second lightguide index n_(G2) where the second light guide index n_(G2) is lessthan or equal to that of the TIR structure 112 (i.e., n_(G2) n₁), andwhere the relationship between n_(G1) and n_(G2) and where the angle ofthe materials 122 ₁, 122 ₂ relative to each other, are configured tocause the incoming light to bend to enter the TIR structure 112 at anangle appropriate to cause the light to enter the TIR structure 112 atan angle suitable for TIR within the TIR structure 112. While notexpressly shown by FIG. 2 , n_(G1) may be the same as the index ofrefraction of the light collection element 124 (if present) or the sameas the surrounding material or air.

In some embodiments, the waveguide entrances 120 may include acollection element 124, e.g., a lens or lens system (e.g., as shown inFIG. 2 ), where the collection element 124 is configured to increase theamount of external light 140 that is input into the waveguide 110. Forexample, in some embodiments, collection element 124 collimates thecollected light 140 to increase the amount of collected light thatenters the TIR structure 112 at the TIR angle. Thus, collection element124 enables more light to be captured for light communications, evenlight that enters the waveguide 110 at an angle. When the waveguideentrance 120 includes a collection element 124, generally the collectionelement 124 will have a wide Field of View (FoV) to increase the amountof collected light. Exemplary collection elements 124 include, but arenot limited to a Fresnel lens 124 a (FIG. 5 ), a plano-convex lens 124 c(FIG. 5 ), etc. It will be appreciated that the use of any collectionelement 124 in one or more waveguide entrances 120 is optional. In someexemplary embodiments, the light guide structure 122 and thecorresponding lens 124 collectively form a dual layer Fresnel lens,where the lens 124 is a first (top) layer of the dual layer Fresnel lensthat collects the light 140 and light guide structure 122 is a second(bottom) layer of the dual layer Fresnel lens that directs the lightinto the TIR structure 112 at the TIR angle. In this example, a first(top) side of the light guide structure 112 is adjacent to the lens 124and receives the collected light, while a second (bottom) side of thelight guide structure 122 abuts the TIR structure 112 and directs thecollected light into the TIR structure 112 at a TIR angle while alsomaintaining the TIR of any light already propagating within the TIRstructure 112.

The waveguide entrance 120 farthest along the waveguide 110 from thesensor 130, referred to herein as the initial waveguide entrance 120 a,may be configured to maintain TIR of light already propagating withinthe TIR structure 112, but such is not required. In some embodiments,the initial waveguide entrance 120 a may employ a different type ofguiding structure than discussed above to facilitate the propagation ofthe collected light into the TIR structure 112 without the requirementto maintain the propagation of any already propagating light (for thesole reason that no light has been collected prior to this initialwaveguide entrance 120 a). For example, FIGS. 3 and 4 show waveguides110 comprising a light guiding element 118 opposite the initialwaveguide entrance 120 a that is configured to facilitate thepropagation of the collected light from the initial waveguide entrance120 a along the TIR structure 112. In one exemplary embodiment, thelight guiding element 118 comprises a reflector configured to reflectthe light collected by the corresponding initial waveguide entrance 120a at a total internal reflection angle to facilitate the propagation ofthe collected light along the TIR structure 112. One exemplary reflectorincludes an angled mirror 118, as shown in FIG. 3 , which reflects theincident light at an angle θ equivalent to the entry angle θ. Toimplement the total internal reflection, this angle θ may be equivalentto the total internal reflection angle for the waveguide 110. While FIG.3 only shows the initial waveguide entrance 120 a, it will beappreciated that other waveguide entrances 120 may be included asdiscussed herein. Additional reflectors include, but are not limited to,a plurality of etched surfaces, as shown in FIG. 4 , mirror print or amaterial with a lower refractive index so that the angle θ of the lightexiting the light guiding element 118 is the same as the angle ofincidence on the light guiding element 118, etc. In another exemplaryembodiment, the light guiding element 118 comprises a bend proximate thecorresponding initial waveguide entrance 120 a (not shown), where thebend is configured to direct the collected light at the total internalreflection angle to facilitate the propagation of the collected lightalong the TIR structure 112.

The exemplary light detection systems 100 of FIGS. 1-4 show waveguideentrances 120 all laterally offset from to one lateral side of sensor130 in one direction providing light to the sensor 130. The solutionpresented herein, however is not so limited. Alternative embodiments mayinclude multiple waveguide entrances 120 on either side of the sensor(along the waveguide 110) that collect light for propagation along oneor more corresponding waveguides 110 to the sensor 130. FIG. 5 shows anexemplary embodiment with multiple waveguide entrances 120 on opposingsides of the sensor 130 channeling light to the sensor 130. As shown inFIG. 5 , light sensor 130 may detect light originating from waveguideentrance 120 a and waveguide entrance 120 b located on opposing sides ofthe TIR waveguide 110 from the light sensor 130. In this exemplaryembodiment, waveguide entrance 120 a and lens 124 a collects light 140a, light guiding element 118 a establishes the TIR angle for thecollected light to propagate 116 a the collected light along the TIRstructure 112 towards the sensor 130 in a first direction. Further,waveguide entrance 120 c and lens 124 c collects light 140 c, lightguiding element 118 c establishes the TIR angle for the collected lightto propagate 116 c the collected light along the TIR structure 112towards the sensor 130 in a second direction opposite the firstdirection. The diffusive element 114 disrupts the propagation 116 a, 116c, from both directions, of the light collected by the waveguideentrances 120 a, 120 c for detection by sensor 130. While FIG. 5 showseach waveguide entrance 120 having a light guiding element 118, it willbe appreciated that one or both of these waveguide entrances 120 mayalternatively include the light guide structure 122, e.g., shown in FIG.2 . Further, while FIG. 5 shows only one waveguide entrance 120 on eachside of the sensor 130, it will be appreciated that the solutionpresented herein allows for multiple waveguide entrances 120 on eitherside, or on both sides, of the sensor 130. For example, one or moreadditional waveguide entrances 120 may be disposed between waveguideentrance 120 a and sensor 130, as shown in FIG. 1 , and/or betweenwaveguide entrance 120 c and sensor 130.

In some embodiments, multiple waveguide entrances 120 use the samewaveguide 110 to propagate the light to a single sensor 130, e.g., asshown in FIGS. 1-5 . In other embodiments, multiple waveguides 110propagate light from two or more waveguide entrances 120 to a singlesensor 130. In addition, the location of one or more waveguide entrances120 relative to the sensor may be selected to reduce noise and/orincrease the signal strength. For example, the lateral spacing betweenmultiple waveguide entrances 120 and the corresponding sensor 130 may beconfigured such that the light entering the sensor 130 addsconstructively. Alternatively or additionally, the lateral spacingbetween multiple waveguide entrances 120 and the corresponding sensor130 may be configured such that interference present in the collectedlight adds destructively or neutrally.

While FIGS. 1-5 show exemplary detection systems 100 having only onesensor 130, it will be appreciated that the detection system 100disclosed herein may include more than one sensor 130. Further, whileFIGS. 1-5 show exemplary detection systems 100 having 1-3 waveguideentrances 120, it will be appreciated that the detection system 100disclosed herein may include any number of waveguide entrances 120. Ingeneral, detection system 100 may comprise any number of waveguideentrances 120 and/or waveguides 110, where each waveguide entrance 120is located at a location of the waveguide 110 laterally offset from thesensor 130 and diffusive element 114, such that light communications areimplemented using fewer sensors 130 than waveguide entrances 120 and/orwaveguides 110. In so doing, the solution presented herein reduces thenumber of sensors 130 associated with light communications, whilesimultaneously improving the quality of the light communications, e.g.,by increasing the amplitude of the detected light. Further, by usingwaveguides to direct the light from multiple entrances 120 to thesensor(s) 130, the solution presented herein relaxes limitationspreviously placed on the sensor(s) 130, e.g., the size, power, etc.,because the sensor(s) 130 may now be placed at any suitable location inthe device 200.

FIG. 6 shows an exemplary method 300 of detecting light associated withlight communications. The method comprises collecting (block 310) lightconfigured for the light communications via two or more waveguideentrances 120 disposed at different locations along a total internalreflection TIR waveguide 110. The TIR waveguide 110 comprises a TIRstructure 112 having a first index of refraction n₁, where a secondindex of refraction n₂ and/or n₃ adjacent the TIR structure 112 is lessthan the first index of refraction n₁ such that light entering the TIRwaveguide 110 propagates along the TIR waveguide 110 within the TIRstructure 112. The method further comprises maintaining (block 320), ateach of at least one of the two or more waveguide entrances 120, totalinternal reflection of light already propagating along the TIR waveguide110 within the TIR structure 112. The method further comprisesdisrupting (block 320) the propagation of the light along the TIRwaveguide 110 using a diffusive element 114 disposed along an internaledge of the TIR structure 112 at a first location of the TIR waveguide110. The first location is offset (laterally) along the TIR waveguide110 from each of the locations of the two or more waveguide entrances120. The method further comprises detecting (block 340) the disruptedlight using a light sensor 130 disposed adjacent an edge of the TIRstructure 112 opposite the first location and spaced from the diffusiveelement 114 by a thickness t of the TIR structure 112.

As mentioned above, the light detection system 100 of the solutionpresented herein may be implemented in and/or as part of any number ofwireless devices 200 that implement light communications. Exemplarydevices 200 may be worn and/or carried by a user, where the lightdetection system 100 disclosed herein may be internal to a housing of adevice 200, disposed partially internally to the device 200 andpartially integrated with/disposed on the housing of the device, orimplemented on an external surface of the housing of the device 200.

FIGS. 7A-7C show an exemplary smart phone device 200. Smart phone device200 may comprise waveguide entrances 120 around the display 220 alongthe perimeter of the housing 210, as shown in FIG. 7A. Alternatively oradditionally, device 200 may comprise waveguide entrances 120 on a backof the smart phone device 200, as shown in FIGS. 7B and 7C. It will beappreciated that sensor 130 may be disposed at any location along thewaveguide 110. For example, sensor 130 may be disposed at the end of thewaveguide 110 such that the sensor 130 captures light form multiplewaveguide entrances 120 disposed along the waveguide leading up to thesensor 130, e.g., as shown in FIG. 7B. In another example, the sensor130 may be disposed somewhere between the ends of the waveguide suchthat the sensor 130 captures light form multiple waveguide entrances 120disposed along the waveguide leading up to the sensor 130 in twodifferent directions, e.g., as shown in FIG. 7C. In the example of FIG.7C, the waveguide 110 may include two initial waveguide entrances 120 a,e.g., at each end of the waveguide 110. Further, while not explicitlyshown, it will be appreciated that the waveguide entrances 120 may beintegrated with the display 220. It will be appreciated that theintegration of waveguide entrance(s) 120 with the display 220 mayinclude placing the waveguide entrance(s) 120 below a transparent typeof display 220, e.g., an Active-Matrix Organic Light-Emitting Diode(AMOLED) screen/display. It will further be appreciated that thewaveguide solution presented herein enables multiple waveguide entrances120 to be placed at any suitable location on the smart phone device 200,besides those explicitly shown, while simultaneously enabling a singlesensor 130 (or fewer sensors 130 than there are waveguide entrances120), placed in the device 200 at any location suitable for the sensor130, to detect the light from the multiple entrances 120, and thusenable the light communications.

In another exemplary embodiment, the device 200 comprises a watch, asshown in FIG. 8 . For the watch embodiment, the waveguide entrances 120may be placed at any suitable location, e.g., around the face 230 of thewatch and/or in a bezel of the watch, integrated with the display of thewatch (not shown), as part of the face of the watch (not shown), etc. Inyet another exemplary embodiment, shown in FIG. 9 , the device 200comprises glasses, where the waveguide entrances 120 are disposed alonga frame 240 of the glasses. In addition to the smartphone, watch, andglasses implementations discussed herein, the solution presented hereinis also applicable to any wireless devices implementing lightcommunications. For example, other exemplary devices 200 include, butare not limited to, hearing aids, fitness monitors, cellular telephones,laptop computers, tablets, etc.

The solution presented herein accommodates multiple collection pointsalong the waveguide by configuring each waveguide entrance, or at leastall but the first waveguide entrance farthest along the waveguide fromthe sensor (i.e., the initial waveguide entrance), to not only collectand input light into the waveguide, but also to maintain the totalinternal reflection of the light already propagating within the TIRstructure. By using multiple waveguide entrances to provide light to asingle sensor, the solution presented herein increases the amount oflight available for light communications, even when the light associatedwith the light communications enters the device at an angle. Further,because each waveguide channels light from multiple collection points toa single sensor, the solution presented herein reduces the number ofsensors needed for the light communications.

The present invention may, of course, be carried out in other ways thanthose specifically set forth herein without departing from essentialcharacteristics of the invention. The present embodiments are to beconsidered in all respects as illustrative and not restrictive, and allchanges coming within the meaning and equivalency range of the appendedclaims are intended to be embraced therein.

1-23. (canceled)
 24. A total internal reflection (TIR) waveguidecomprising: a TIR structure operative to internally propagate lightalong the TIR waveguide; a first waveguide entrance disposed along theTIR waveguide and configured to collect a first portion of the lightinto the TIR structure; and a second waveguide entrance disposed alongthe TIR waveguide and spaced away from the first waveguide entrance,wherein the second waveguide entrance is operative to collect a secondportion of the light into the TIR structure and maintain TIR of thefirst portion of the light already propagating along the TIR waveguidewithin the TIR structure.
 25. The TIR waveguide of claim 24, furthercomprising a diffusive element disposed along an internal edge of theTIR structure, the diffusive element configured to disrupt thepropagation of the light along the TIR waveguide.
 26. The TIR waveguideof claim 25, wherein the diffusive element is further configured todirect at least some of the disrupted light toward a light sensordisposed adjacent to the TIR structure.
 27. The TIR waveguide of claim25, further comprising a light guiding element disposed along aninternal edge of the TIR structure opposite the first waveguideentrance, the light guiding element being operative to facilitatepropagation of the first portion of the light along the TIR waveguideand the first waveguide entrance being farther along the TIR waveguidefrom the diffusive element than the second waveguide entrance.
 28. TheTIR waveguide of claim 24, wherein to internally propagate the lightalong the TIR waveguide, the TIR structure is operative to internallypropagate the first portion of the light and the second portion of thelight in a same direction.
 29. The TIR waveguide of claim 24, furthercomprising a third waveguide entrance spaced apart from the firstwaveguide entrance and the second waveguide entrance, wherein: the thirdwaveguide entrance is operative to collect a third portion of the light;and to internally propagate the light along the TIR waveguide, the TIRstructure is operative to internally propagate the third portion of thelight and the first portion of the light in opposing directions.
 30. TheTIR waveguide of claim 24, wherein the second waveguide entrancecomprises a light guide structure that abuts the TIR structure and isoperative to direct the second portion of the light into the TIRstructure at an angle conducive for TIR reflection within the TIRstructure.
 31. The TIR waveguide of claim 30, wherein to collect thesecond portion of the light into the TIR structure: the second waveguideentrance further comprises a lens operative to collect the secondportion of the light into the light guide structure at a first side ofthe light guide structure adjacent to the lens; and a second side of thelight guide structure is opposite the first side and abuts the TIRstructure, the second side being operative to: direct the second portionof the light into the TIR structure at the angle conducive for TIRreflection within the TIR structure; and maintain TIR of the firstportion of the light already propagating along the TIR waveguide withinthe TIR structure.
 32. The TIR waveguide of claim 24, further comprisinga multi-layer coating having at least three layers, the TIR structurecomprising a middle layer of the multi-layer coating.
 33. The TIRwaveguide of claim 32, wherein the multi-layer coating comprises: afirst layer adjacent the first waveguide entrance, the second waveguideentrance, or both; the middle layer abutting the first layer; and asecond layer abutting the middle layer.
 34. The TIR waveguide of claim32, wherein the multi-layer coating is at least partially disposed on anexternal portion of a device comprising a detection system configured todetect the light.
 35. A method of propagating light through a totalinternal reflection (TIR) waveguide, the method comprising: collecting afirst portion of the light into a TIR structure of the TIR waveguide ata first waveguide entrance disposed along the TIR waveguide; collectinga second portion of the light into the TIR structure at a secondwaveguide entrance disposed along the TIR waveguide and spaced away fromthe first waveguide entrance; propagating the light along the TIRwaveguide within the TIR structure, the propagating comprisingmaintaining, at the second waveguide entrance, TIR of the first portionof the light.
 36. The method of claim 35, further comprising disruptingthe propagation of the light along the TIR waveguide using a diffusiveelement disposed along an internal edge of the TIR structure.
 37. Themethod of claim 36, further comprising directing at least some of thedisrupted light toward a light sensor disposed adjacent to the TIRstructure.
 38. The method of claim 36, further comprising facilitatingpropagation of the first portion of the light along the TIR waveguideusing a light guiding element disposed along an internal edge of the TIRstructure opposite the first waveguide entrance, the first waveguideentrance being farther along the TIR waveguide from the diffusiveelement than the second waveguide entrance.
 39. The method of claim 35,wherein propagating the light along the TIR waveguide within the TIRstructure comprises internally propagating the first portion of thelight and the second portion of the light in a same direction.
 40. Themethod of claim 35, further comprising collecting a third portion of thelight into the TIR structure at a third waveguide entrance spaced apartfrom the first waveguide entrance and the second waveguide entrance,wherein propagating the light along the TIR waveguide within the TIRstructure comprises internally propagating the third portion of thelight and the first portion of the light in opposing directions.
 41. Themethod of claim 35, further comprising directing the second portion ofthe light into the TIR structure at an angle conducive for TIRreflection within the TIR structure using a light guide structure of thesecond waveguide entrance that abuts the TIR structure.
 42. The methodof claim 41, wherein collecting the second portion of the light into theTIR structure at the second waveguide entrance comprises: collecting thesecond portion of the light into the light guide structure at a firstside of the light guide structure using a lens of the second waveguideentrance that is adjacent to the first side; and directing the secondportion of the light into the TIR structure at the angle conducive forTIR reflection within the TIR structure at a second side of the lightguide structure that is opposite to the first side and abuts the TIRstructure; and wherein the method further comprises maintaining, at thesecond side of the light guide structure, TIR of the first portion ofthe light propagating along the TIR waveguide within the TIR structure.43. A wireless device comprising: a housing; and a total internalreflection (TIR) waveguide disposed at least partially within thehousing, the TIR waveguide comprising: a TIR structure operative tointernally propagate light along the TIR waveguide; a first waveguideentrance disposed along the TIR waveguide and configured to collect afirst portion of the light into the TIR structure; and a secondwaveguide entrance disposed along the TIR waveguide and spaced away fromthe first waveguide entrance, wherein the second waveguide entrance isoperative to collect a second portion of the light into the TIRstructure and maintain TIR of the first portion of the light alreadypropagating along the TIR waveguide within the TIR structure.
 44. Thewireless device of claim 43, wherein the TIR waveguide further comprisesa diffusive element disposed along an internal edge of the TIRstructure, the diffusive element configured to disrupt the propagationof the light along the TIR waveguide.
 45. The wireless device of claim44, further comprising a light sensor adjacent to the TIR structure,wherein the diffusive element is further configured to direct at leastsome of the disrupted light toward the light sensor.
 46. The wirelessdevice of claim 45, wherein the light sensor is comprised in a detectionsystem of the wireless device that is configured to interpret thedisrupted light received by the light sensor as light communicationsignaling.
 47. The wireless device of claim 43, wherein to internallypropagate the light along the TIR waveguide, the TIR structure isoperative to internally propagate the first portion of the light and thesecond portion of the light in a same direction.
 48. The wireless deviceof claim 43, wherein the housing comprises at least one opening throughwhich the first and second portions of the light are collected by thefirst and second waveguide entrances, respectively.
 49. The wirelessdevice of claim 43, wherein the housing is configured to be worn by auser.